U.S. Pat. No. 5,140,222, Roznerski, discloses a high pressure discharge lamp of the type to which the present invention relates. This lamp has a fill which includes xenon. The lamp has a quartz glass bulb which defines a lamp axis. Two neck portions extend from the bulb in alignment with the axis. The lamp necks are provided with conically shaped support elements made of quartz glass, and with ceramic disks movably located in the lamp necks, and pressed by a spring to a constricted zone of the neck portions and the lamp.
Plug elements in the form of glass cylinders have been used in mercury arc high pressure discharge lamps for support of electrode connecting or holding rods. These glass cylinders are melt-connected to the necks extending from the bulb, and have a smooth generally cylindrical outer surface on which the melt connection is formed. The lamps described in the referenced U.S. Pat. No. 5,264,759, Lewandowski et al, U.S. Pat. No. 5,304,892, Lewandowski et al, and German Publication DE 196 18 967 A1 have such support tubes which, at least in the transition region to the bulb, have a constant wall thickness throughout their length. Thus, the outer diameter as well as the inner diameter of the support tubes are defined by the diameter of the foil melt connection in the more remote portion of the necks of the lamps. The support tubes usually were fitted directly at the beginning of the neck portion, and melt connected with the wall of the bulb in the region of the neck. This technology permitted only mercury fills up to a maximum of 20 mg/cm.sup.3 and relative small bulb dimensions, to an overall length of about 80 mm. If higher pressure is used, the risk of bursting increases, since the stress accepting capability in the region of the transition of discharge space to the neck is exceeded.